EsR240, a non-coding sRNA, is required for the resistance of Edwardsiella tarda to stresses in macrophages and for virulence

In this study, 13 novel sRNAs were identified in the intracellular pathogen, Edwardsiella tarda (E. tarda) ET13 strain, based on RNA sequencing and bioinformatic analyses. Eight of the 13 putative sRNAs from the ET strain were transcribed (as indicated by RT-PCR) following exposure to different stresses. The transcription levels of three sRNAs (EsR128, EsR139, and EsR240) were all highly induced under these stress conditions. Northern blot hybridization was employed to verify that EsR240 was expressed in the ET13 strain under both logarithmic and stationary growth phases, and that it formed a single copy transcript in the chromosomes of the ET13 strain. The precise start and end points of EsR240 were determined using 5’and 3’ RACE. The conservation of EsR240 was in agreement with the characteristics of the sRNA, as indicated by a BLAST analysis. Furthermore, the survival rates of the EsR240 mutant were lower than the rates of the wild type bacterium under stress conditions. When the infection time was extended 4 or 6 h, the CFUs of the wild type bacteria increased more significantly within macrophages compared to the mutant. When the intra-peritoneal (i.p.) route of infection was used in mice, the bacterial loads of the tissues in the mice infected with the wild type bacteria were significantly higher than in the mice infected with the mutants. The virulence of the EsR240 mutant was 6.79-fold lower than the wild type bacterium based on the LD50. In addition, the IntaRNA p...
Source: Veterinary Microbiology - Category: Veterinary Research Source Type: research